Method for welding a welded part to a component and use of a welded part

Abstract

A method for welding a welded part to a component is carried out as arc ignition welding by use of direct current, having a bias current phase in which an arc is formed between the negatively polarized welded part and the component, and a subsequent main current phase for melting material to the joint. The welded part: a) is a galvanized sphere made of C10C having a roundness G500, wherein the size of any zinc inclusions under the surface of the sphere equals 10 micrometers at maximum, orb) is formed by welding a galvanized sphere made of C10C having a roundness G500, wherein the size of any zinc inclusions under the surface of the sphere equals 10 micrometers at maximum, to a connection element.

What is claimed is: 
     
       1. A method for welding a welded part to a component, which is carried out as drawn arc welding with DC current, the method comprising:
 a preweld current phase, in which an arc is formed between a negatively polarized welded part and the component; and 
 a subsequent main current phase for melting material at a joining point, 
 wherein the welded part: 
 a) comprises a galvanized ball of C10C with a roundness of G500, in which a size of any zinc inclusions below a surface of the ball is a maximum of 10 micrometers, 
 or 
 b) is formed by the welding of a galvanized ball of C10C with a roundness of G500, in which a size of any zinc inclusions below a surface of the ball is a maximum of 10 micrometers, to a connecting element. 
 
     
     
       2. The method according to  claim 1 , wherein
 the welded part is formed as a double ball by welding of a galvanized ball of C10C with a roundness of G500, in which the size of any zinc inclusions below the surface of the ball is a maximum of 10 micrometers, to a second such galvanized ball. 
 
     
     
       3. The method according to  claim 1 , wherein
 the material C10C of the galvanized ball has a degree of purity in accordance with DIN 10247/2007-07 of K3≤15. 
 
     
     
       4. The method according to  claim 1 , wherein
 a ball that has a roundness of G100 before coating to form a zinc layer is used as the galvanized ball. 
 
     
     
       5. The method according to  claim 1 , wherein
 a thickness of a zinc layer of the galvanized ball lies in the range from 6 to 12 micrometers. 
 
     
     
       6. The method according to  claim 1 , wherein
 the component is a sheet steel component. 
 
     
     
       7. The method according to  claim 1 , wherein
 the component is a body component of a motor vehicle. 
 
     
     
       8. The method according to  claim 1 , wherein
 a single main current value is predetermined during the main current phase and the main current phase lasts for a predetermined welding time. 
 
     
     
       9. The method according to  claim 1 , wherein
 the welded part is the galvanized ball, and 
 the main current phase has three successive main current subphases, wherein
 a first main current value is predetermined in the first main current subphase, 
 a second main current value, which is reduced in comparison with the first main current value, is predetermined in the second main current subphase, and 
 a third main current value, which lies between the first main current value and the second main current value, is predetermined in the subsequent third main current subphase. 
 
 
     
     
       10. The method according to  claim 9 , wherein
 the first main current value is 130% to 150% of a reference main current value and the time duration of the first main current subphase is 10% to 15% of a reference time, 
 the second main current value is 23% to 43% of the reference main current value and the time duration of the second main current phase is 10% to 15% of the reference time, and 
 the third main current value is 70% to 90% of the reference main current value and the time duration of the third main current phase is 50% to 70% of the reference time, 
 wherein the reference main current value and the reference time correspond to the main current value and the welding time that would be predetermined for a welding of the galvanized ball to a sheet steel component. 
 
     
     
       11. The method according to  claim 10 , wherein
 the first main current value is 140% of a reference main current value and the time duration of the first main current subphase is 12.5% of a reference time, 
 the second main current value is 33% of the reference main current value and the time duration of the second main current phase is 12.5% of the reference time, and 
 the third main current value is 80% of the reference main current value and the time duration of the third main current phase is 60% of the reference time, 
 wherein the reference main current value and the reference time correspond to the main current value and the welding time that would be predetermined for a welding of the galvanized ball to a sheet steel component. 
 
     
     
       12. The method according to  9 , wherein
 the component is a thin sheet with a sheet thickness of 0.7 mm or less or a thick sheet with a sheet thickness of 1.5 mm or greater. 
 
     
     
       13. Use of a welded part in a method for drawn arc welding according to  claim 1 , wherein
 the welded part comprises the galvanized ball of C10C with a roundness of G500, in which the size of any zinc inclusions below the surface of the ball is a maximum of 10 micrometers. 
 
     
     
       14. Use of a welded part in a method for drawn arc welding according to  claim 1 , wherein
 the welded part is formed by the welding of a galvanized ball of C10C with a roundness of G500, in which the size of any zinc inclusions below the surface of the ball is a maximum of 10 micrometers, to a further galvanized ball of C10C with a roundness of G500, in which the size of any zinc inclusions below the surface of the ball is a maximum of 10 micrometers.